JAMB Biology Past Questions & Answers - Page 56

276.

Floating microscopic heterotrophs are mostly grouped as

A.

phytoplankton

B.

zooplankton

C.

microbes

D.

nekton

Correct answer is B

Phytoplankton are microscopic marine organisms that sit at the bottom of the food chain, most phytoplankton are buoyant and float in the upper part of the ocean. However, they are not heterotrophic like the zooplanktons.

microbes are living organisms around us that we can't see with our naked eyes.

nektons are organisms that are able to swim and move independently of current.

277.

The biological association that contributes directly to succession in a community is

A.

competition

B.

predation

C.

parasitism

D.

commensalism

Correct answer is A

competition between species in a particular habitat is a biotic factor of ecological primary succession.

278.

A group of organisms of different species living in a particular area is described as a

A.

colony

B.

community

C.

population

D.

niche

Correct answer is B

A community is formed by populations of different species living together and interacting with each other. A community forms an ecosystem by its interaction with the abiotic environment.

279.

The arrangement of ovules attached to the sides of a syncarpous ovary with a single chamber is referred to as

A.

free-central placentation

B.

axile placentation

C.

parietal placentation

D.

marginal placentation

Correct answer is C

No explanation has been provided for this answer.

280.

The ability of the eyes to focus on both near and distant objects is termed

A.

image formation

B.

refraction

C.

hypermetropia

D.

accommodation

Correct answer is D

The ability of the eye to focus on distant and near objects clearly on the retina of the eye is called accommodation. When our eyes see distant objects then the ciliary muscles relax and the focal length is maximum in this position.